Apparatuses for the hot production of strip starting from the casting of thin slabs are known.
One example of this apparatus, identified by the number 510, is shown by way of example in FIG. 1.
The apparatus 510 comprises a casting line 511 for thin slabs and a rolling line 513 located downstream and aligned with the casting line 511. A tunnel furnace 512 is normally present directly downstream of the casting line 511 to heat and/or maintain the slabs at a certain temperature before they are rolled.
The rolling line 513 is provided with a plurality of roughing stands 514 and finishing stands 515 disposed in sequence and in which the thin slab is progressively reduced in thickness to obtain, for example, strip.
It is known that some types of materials, for example, steels with particular mechanical and/or chemical characteristics, such as alloy steels, special steels, peritectic steels, stainless steels, are not easily castable as thin slabs, but must be cast with greater thicknesses; for example, the thicknesses of conventional slabs, and therefore would not be workable in the plant as in FIG. 1.
FIG. 2 shows another example of an apparatus, identified by the reference number 610, which is suitable to work conventional slabs. This apparatus comprises a plurality of heating furnaces 516, also called “walking beam furnaces”, provided to heat, up to a temperature suitable for rolling, conventional slabs which are at ambient temperature, for example arriving from a storage zone. The heating furnaces 516 are aligned with the rolling line 513 located downstream. The rolling line 513 comprises reversing roughing stands 514, finishing stands 515, and devices 517 for rolling the edges, also called “edgers”.
Moreover, between the roughing stands 514 and the finishing stands 515, a winding/unwinding device can be interposed, to wind the rolled product received from the roughing stands 514 and to unwind it and feed it to the finishing stands 515.
Apparatuses for the production of strip are also known which allow to work both thin slabs and conventional slabs which are rolled to obtain strip.
An example of this known apparatus is shown in FIG. 3 with the reference number 710, which comprises a casting line 511 for thin slabs located in line with a tunnel furnace 512, and with a rolling line 513.
The rolling line 513 is provided with roughing stands 514 and finishing stands 515.
The apparatus 510 is also provided with an auxiliary rolling line 519 having a rolling unit 520 configured to roll conventional slabs, which, once pre-rolled by the rolling unit 520 disposed along the auxiliary rolling line 519, are fed laterally to the tunnel furnace 512 to be further rolled in the rolling line 513.
This solution, although it increases the efficiency and productivity of the plant, is very bulky, very costly and difficult to apply to existing plants through operations of renewal and expansion.
Other examples of rolling apparatus are described in documents U.S. Pat. Nos. 6,941,636 and 5,544,408.
One purpose of the present invention is to provide an apparatus for the hot production of metal strip and to implement a method which allows to obtain finished strip having uniform and homogeneous dimensional qualities and mechanical properties for a wide range of steels (steel grade).
Another purpose of the present invention is to provide an apparatus for the production of strip which has limited bulk.
Another purpose of the present invention is to provide an apparatus for the production of strip which has lower investment and maintenance costs compared to known systems.
Another purpose of the present invention is to provide an apparatus and a method for rolling slabs which is easily applicable to existing continuous casting plants.
Another purpose is to perfect a method for the production of metal products with homogeneous qualities starting from both thin slabs and conventional slabs.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.